Vinyl polysiloxane compositions



Patented July 14, 1953 :Dallas T. Hurd, Burnt Hills, N. Y., ,assignor toGeneral Electric Company, .a corporation of New York N Drawing.Application'March 30,1951,

Serial N0. 218,537

This application is a continuation-in-part of my earlier filedapplication, .Serial No. 598,928,

'filed June '11, 1945,1and'assigned'to the same assignee as thepresentinvention, the aforesaid application now "being abandoned.

"The present invention .relates to resinous or polymerizablepolysiloxane compositions containing both silicon-bonded 'vinyl radicalsand silicon-bonded monoval'ent hydrocarbon radicals selected fromtthegroup consisting of alkyl, aryl, 'aralkyl, and alkaryl radicals, andto'copolymers containing such .polysiloxanes.

"Ihe term"polysiloxane, as used herein, refers to compositions of matterhavingiasskeletalrstructure consisting essentially of alternate atoms ofsilicon and oxygen. The structures resulting from thesilicon-oxygen-siliconlinkages may be either of a cyclic orstraight-chain or branched-chain type, or any combination of one or moreof these types resulting from cross-linking of the, basic units at oneor more points by additional silicon-oXygen-silicon linkages to form anet-- work structure.

Various hydrocarbon-substituted polysiloxane compounds haveheretoforebeen known. 'Many,

of these have'been described or referred to, for example, in Rochow U.S. Patents 2,258,21'8-222, assigned to the same assignee as the presentin vention. In these known polysiloxanes, particularly the resinouspolysiloxanes such as are described in the Rochow patents mentionedabove, all of the silicon-bonded monovalent hydrocarbon radicals aresaturated aryl or saturated'alkyleradicals, the cross-linking necessaryfor the iormaby Si-O-Si linkages.

The *po'lysiloxanes of the presentinventicn are distinguished from thepolysiloxanes known here- .to'foreby the fact that part ofthesilicon-bonded hydrocarbon radicals, particularly'the saturatedhydrocarbon radicals, are substituted "by shortchain, moncvalent,terminally unsaturated al kenyhradicails, specifically,--vinyl radicals,so that further polymerization of the polysiloxanes can beefiectedthrough lthese unsaturated radicals. The vinyl radicals may--be:substituted on .silicon .atoms which have no other organic-radicalattached thereto, or the vinyl radicals :may be attached tosiliconsatoms which also contain a nonyinylic hydrocarbon radical, e. gmeth-yl phenyl, etc. By substitution tof the vinyl radicals for minorproportions of the silicon-bonded monovalent hydrocarbonra'dic'als ofthe known polysiloxanes, particularly useful products canbe obtainedhaving -the characteristic propertiesioi the 6 Claims. (01. 2s.0 .4e. 5)

polysilo-xane structure and the added advantage resulting from thecapacity .of the vinyl substi tuents to undergo e-organic polymerizationwith the formationtofjlargerunclecules. In general,

, although a-llylgroups attached to silicon appear to be more reactivetowardpolymerization than the vinylqgroupswith which the presentinvention-lis concernedgit has been foundthatunderequivalent-molarconcentrations of vinyl and allyl groups,theremainingestructure of the organopolysiloxane beingaessenti-ally thesame, the heat-stability f organopolysiloxanes containing vinyl groupsis better than the heat-stability of organopolysiloxanes inwhichallylgroups are present in place of vinyl groups.

The vinyl-substituted silicon halides which are used to make theorganopolysiloxanes herein described and claimed may be prepared invarious ways. For example, -a vinyl halide, for instance,

vinyl chloride-or vinyl bromide, may be reacted withheated silicon inthepresence'of acopper catalystin accordancewith the processdescribed andclaimedin :myU. S. Patent 2,420,912, issued 'May"20,,l947, and-assignedto the-same assignee as "the'presentinvention Alternatively, an ethylsilicon :ihalide, such as ethyltrichlorosilane, or.ethylmethyldichlorosilane can bechlorinated in the ethyltradical:thereof,:for example, by means of sulfurylich'loride, :and thechloroethyl groups su'bjectedtto dehydrochlorination to form the cor-:responding-;vinylasubstituted silane. Thismay be accomplished, forexample, by heating the chloroethyl derivative with :an excess :ofquinoline or other suitable tertiary amine.

'tion of solid or resinousm'aterials being obtained Theprincipaladvantages-of'the present inven- 1- which, "in :turn, 'arenormally prepared by hydrolys'is of silane derivatives orlmixturesofcsuch silan'es of t-he' formula RriSiXia wherein -12 is a number from"1 to 3,*R:represents arnonovalent hydrocarbon radical :and .Xrepresents a hydrolyzable group, suchiasa halogen atom, an

alkoxy radical or the. like. ,A compound of the formula SiXi where X is"a hydrolyzable group as above, such ass-ilicen tetrachloride, may alsobepresent to introduce'greater functionality-and ,50 cross-11inkingduring hydrolysis. In the preparation :of1polysiloxanes,particularlythe resinous uran'd "other :highmolecular weight materials, thecharacteristics of the fully condensed products .iare'primar ily:dependent :on the particular silane tor ssilanes employed as starting,materials, ;i. (2.,

the nature and average number of silicon-bonded R groups so that thefinal products will be either liquid or resinous depending on theaverage R/ Si ratio of the silicol or silicols. Except for certaintreatments believed to result in a rearrangement of the condensation,products or a removal of R groups, the main, and, in general, the onlyreaction involved in the preparation of the polysiloxanes subsequent tothe hydrolysis of the starting materials is the condensation orintercondensation of silicols. Hence, control of the formation of thepolysiloxanes wherein R is, e. g., an alkyl or aryl group, essentiallydepends on the degree to which the condensation reactions can becontrolled.

'comitant polymerization of silicon-bonded vinyl radicals. In additionto their shorter curing time, as compared with the known alkyl or ararylpolysiloxanes, the vinyl-substituted polysiloxanes possess the furtheradvantages of ouring at lower temperatures and of losing less weightduring cure due to evaporation of low molecular weight components.

When the alkenyl, that is, vinyl content, is less than 25 per cent basedon the molar content of the vinyl-groups, the heat stability of thecured product is, unexpectedly, comparable with that of thecorresponding products containing only non-vinylic or saturated groupsas, for instance, containing only alkyl (e. g., methyl) groups or aryl(e. g., phenyl) groups. The presence of the terminally unsaturated vinylradical also permits the ready copo-lymerization of the polysiloxanes ofthe present invention with various monomeric polymerizable organicmaterials containing a terminally unsaturated pclymerizable CH2=Cgrouping such as, for example, diallyl phthalate, styrene, vinylchloride, acrylic acid, methacrylate acid, methyl methacrylate, ethyla-crylate, as well as other derivatives of acrylic acid and methacrylicacid, for instance, their other esters, their amides, their nitrilcs,etc.

Further advantages of the present invention will become apparent tothose skilled in the art from a consideration of the followingillustrative examples. In the examples below is illustrated thepreparation of preferred hydrocarbon-substituted polysiloxane resins inwhich a minor proportion of the silicon-bonded hydrocarbon radicals arevinyl radicals.

. Example 1 A mixture of 19.2 volumes of dimethyldichlorosilane and 2.8volumes of vinyl methyldichlorosilane, (CI-I2=CH) (CI-1981012, wasdissolved in 1'00 volumes of diethyl ether, and the solution washydrolyzed in an amount of water in excess of that calculated as beingrequired for complete hydrolysis of all the chlorosilanes in thesolution. After separation of the ether and then at 150 C. for 72 hours.

layer and removal of the ether solvent, 0.1 gram of benzoyl peroxide wasadded to the resulting liquid product which had a hydrocarbon to siliconratio of two and which contained, in the copolymer chain, 20 mol percent vinyl methyl siloxane units, (CH2=CH) (CH3)SiO, and mol per centdimethyl siloxane units. This mixture was then heated at C. for 24 hoursAt the end of this period of heating the liquid product had set to ahard, clear resin.

In the above Example 1, it will be noted that the hydrolysis andcondensation products had an R/Si ratio (hydrocarbon-to-silicon ratio)such that no cross-linking by means of siliconoxyge n-silicon bonds ispossible. Thus, if the vinyl groups had not formed a portion of thetotal hydrocarbon or R group content of the siloxane condensationproduct, a resin would not have been obtained under the conditionsspecified but, rather, oils would have been formed. The followingexamples disclose the preparation of polysiloxane resins in which someof the necessarycross-linking is obtained by the oxygen bridge of theSi-O-Si linkage, that is, by having the R/Si ratio less than 2, and theremainder of the cross-linking by polymerization through vinyl groups.In this connection, a determination of the functionality of any reactionmixture must take into account both the silicon-bonded hydroxyl(silanol) groups and the silicon-bonded vinyl groups. For example,whereas the silanol RsSiOI-I (where R is a monovalent hydrocarbonradical), is only monofunctional if R is an alkyl or aryl group, it hasa greater functionality if one, two, or all of the R groups are vinylgroups. I

Example 2 A mixture of 19.2 volumes of dimethyldichloro silane and 5.2volumes of vinyltrichlorosilane was dissolved in 100 volumes of diethylether and the resulting solution was hydrolyzed by adding it to anamount of water which was substantially in excess of that required forcomplete hydrolysis of all the silicon-bonded chlorine atoms. Afterseparation of the other layer and removal of the ether solvent, a liquidpolysiloxane was obtained containing in an intercondensed state about 20mol per cent monovinyl silicone .or siloxane units and 80 mol per centdimethyl silicone or siloxane units. This liquid was heated to 100 C.for 24 hours, then at C. for '72 hours during which time the liquid setto a hard, transparent resin. It is to be noted that while this resinhad a total R-to-Si ratio of 1.8, itsability to form cross-linkedpolymers of comparable'properties was substantially the same as analkyl' or aryl polysiloxane havan R/Si (where R has the meaning givenabove) ratio of only 1.6.

Eacample 3 A mixture of 19.2 volumes of dimethyldichlorosilane, 3.5volumes of methyltrichlorosilane, and 1.3 volumes ofvinyltrichlorosilane was dissolved in diethyl ether and hydrolyzed in anexcess of water, as was done in Example 1. After removal of the solvent,0.1 gram benzoyl perresin which was substantially infusible; andinsoluble at elevated temperatures.

Example 4 A mixture of 9.8 volumes of dimethyldichlorosilane, 13 volumesof diphenyltrichlorosilane, 7 volumes of phenyltrichlorosilana;and 2.6volumes of vinyltrichlorosilane, was dissolved in 100 volumes of diethylether and was: hydrolyzed by pouring the ethereal solution into anamount of water in excess of that required for complete hydrolysis ofall the silicon-bonded chlorine in the chlorosilane. After separationof. the water layer and removal of the ether solvent, the resultingliquid which contained 10 mol per: cent copolymerized monovinyl siloxaneunits, mol per cent copolymerized dimethyl siloxane units, and a 5-0 molper cent total of copolymerized monophenyl and diphenyl siloxane units,was heated at 100 C. for 24 hours and then at. 200 C. for 48hours-during which time the liquid became more viscous so that when itvwas cooled to room temperature it set to a very hard, thermoplasticresin. The R/Si ratio for this resin was 1.7. The ratio of total methyland phenyl groups to silicon atoms was about 1.6. Further heating ofthis thermoplastic material with cure accelerators, such as benzoylperoxide or tertiary butyl perbenzoate would give a harder resin havinga higher softening point.

It will, of course, be apparent to those skilled in the art that insteadof the vinyl methyl polysiloxanes, or vinyl methyl phenyl polysiloxanesdescribed above, other organopolysiloxanes containing silicon-bondedvinyl radicals, as well as different hydrocarbon (or R) radicals bondedto the silicon atoms by carbon-silicon linkages, may be present as, forinstance, other alkyl radicals, e. g., ethyl, propyl, isopropyl, butyl,hexyl, etc.; other aryl radicals as, e. g., biphenyl, naphthyl, etc.radicals; aralkyl radicals, e. g., benzyl, phenylethyl, etc.; alkarylradicals as, e. g., tolyl, ethylphenyl, xylyl, etc., radicals.

The vinyl hydrocarbon-substituted polysiloxanes herein disclosed andclaimed may also be copolymerized with other polymerizable organiccompounds, such as, for example, methacrylate esters, styrene,chlorostyrene, diallyl phthalate, acrylonitrile, vinyl pyridine, etc.Specific copolymers of methacrylate esters and a methyl vinylpolysiloxane in which the silicon atoms of the poly siloxane areconnected to both a methyl and vinyl group, are described and claimed inRoedel Patent 2,420,911 issued May 20, 1947, and assigned to the sameassignee as the present invention. The copolymers of methyl vinylpolysiloxane with styrene are quite plastic when the proportions of thepolysiloxane are less than 50 per cent, while hard, tough, thermoplasticproducts are obtained by the copolymerization of major proportions ofstyrene or chlorostyrene with minor proportions of a methyl vinylpolysiloxane. Clear copolymers of methyl vinyl silicone andacrylonitrile or diethyl maleate have also been prepared. Hard, tough,somewhat opaque products have been obtained by the copolymerization ofvinyl carbazole and a methyl vinyl polysiloxane. The amount ofnonsilicon-containing copolymerizable monomer which can be used inpreparing the compositions described above may, of course, be variedwithin wide limits. Depending on the properties desired for the finalproduct, the polymerizable non-silicon containing compound may vary, forexample, from about 1 to 99 per cent by weight, preferably from 25 6 to75 per cent by weight, based on the total weight of the latter and thevinyl hydrocarbonsubstituted polysiloxane.

In efiecting polymerization of the vinyl hydrocarbon-substitutedpolysiloxanes herein described, various catalysts, in addition to thosewhich have been disclosed above, may be used, such as, for instance,tertiary butyl hydroperoxide-1, di-(tertiary butyl) diperphthalate, etc.The concentrations of the catalysts may be varied within wide limits butgenerally are preferred to be equal to from about 0.1 to 5 per cent, byweight, based on the weight of the polymerizable composition which maybe either the vinyl hydrocarbon-substituted polysiloxane alone orcombinations. of the latter with other copolymerizablenon-silicon-containing monomeric materials.

From the above description, there have. been provided resins orresinifiable siloxanes containing an average of from 1 to not more than3 silicon-bonded hydrocarbon radicals per silicon atom, at least some ofthe hydrocarbon radicals being' 'vinyl groups. The preferred resins arethose obtained when vinyl groups are substituted for up to 25 per centof the total silicon-bonded hydrocarbon groups, for example, total alkylor aryl groups and vinyl groups, in polysiloxanes having an R/Si ratioof from about 1.2 to 2.0. Best results from the standpoint of the heatstability of the hardenable or hardened products,

appear to be obtained when the vinyl content is limited to less than 25per cent, preferably from about 1 to 20 per cent, especially in therange of from about 5 to 20 per cent, of the total hydrocarbon cr Rcontent of the polysilcxane, and when the total R/Si ratio is from about1.4 to 1.8.

The weight loss during removal of the solvent and subsequent heating orcuring of the vinylsubstituted siloxanes is in all cases substantiallysmaller than with the previously known siloxances in which none of the Rgroups are inherently polymerizable, as, for example, alkyl or arylgroups. Resinous vinyl polysiloxanes having R/Si ratios less than 1.8and in which from 10 to 20 per cent of the silicon-bonded hydrocarbonradicals were vinyl groups have shown no signs of crazing or crackingwhen the cured films have been heated for as long as hours at 200 C. Onthe other hand, organopolysiloxanes containing only unsaturatedhydrocarbon groups attached to the silicon atoms by carbonsilicon bonds,particularly vinyl groups, show early crazing when heated for variouslengths of time at 200 C.

It has been found that the vinyl polysiloxanes herein described andclaimed have greater heat stability and chemical stability than similarorganopolysiloxanes in which the vinyl groups present therein arereplaced by allyl radicals. In addition, Whereas silicon-bonded allylradicals may be caused to cleave in the presence of concentratedsulfuric acid or strong alkali to give such by-products as propylene,under similar conditions the amount of cleavage of siliconbonded vinylradicals is considerably less, thus illustrating the improved chemicalstability of the vinyl polysiloxanes herein described over allylpolysiloxanes containing other kinds of hydrocarbon groups, i. e.,non-polymerizable hydrocarbon groups, attached to the silicon atoms inthe polysiloxane chain.

The heat-hardenable polysiloxanes of the present invention alone ormixed with solvents, pigments, driers, etc., can be employed, forexample, as varnishes or enamels for app as protective, decorative orinsulating coatings which, when applied to a base member and airdried orbaked with or without vinyl polymerization catalysts, have a high.degree of resistance to heat and atmospheric conditions. Suchcompositions can also be employed as fillers binders for coilstructures, or in the manufacture of cast, pressed or moulded articlesin a manner Well known in the plastic art.

What I claim as new and desire to secure by Letters Patent of the UnitedStates is:

1. A resinous composition of matter comprising a polymerizablemonovalent hydrocarbonsubstituted polysiloxane wherein the hydrocarbonradicals consist of both (a) vinyl radicals, and (b)' monovalentradicals selected from the class consisting of alkyl and aryl radicals,all the aforementioned hydrocarbon radicals being present in the ratioof from 1.2 to 1.8 total hydrocarbon radicals per silicon atom and aredirectly attached to the polysiloxane silicon atoms by carbon-siliconlinkages, the said vinyl radicals comprising from 1 to 20 per cent ofthe total number of silicon-bonded hydrocarbon radicals.

2. A resinous composition of matter comprising a. polymerizablemonovalent hydrocarbonsubstituted polysiloxane wherein the hydrocarbonradicals attached thereto by carbon-silicon linkagesconsist of both (a)vinyl radicals, and (b) alkyl radicals, all the aforementionedhydrocarbon radicals being present in the ratio of from about 1.2 to 1.8total hydrocarbon radicals per silicon atom and the vinyl radicalscomprise from 1 to 20 per cent of the total number of silicon-bondedhydrocarbon radicals.

3. A resinous composition of matter comprising a polymerizablemonovalent hydrocarbonsubstituted polysiloxane wherein the hydrocarbonradicals attached thereto by carbonsilicon linkages consist of both (a)vinyl radicals, and (b) aryl radicals, all the aforementionedhydrocarbon radicals being present in the ratio of from about 1.2 to 1.8total hydrocarbon radicals per silicon atom and the vinyl radicalscomprise from 1 to 20 per cent of the total number of silicon-bondedhydrocarbon radicals.

4. A resinous composition of matter comprising a polymerizablemonovalent hydrocarbonsubstituted polysiloxane wherein the hydrocarbonradicals attached thereto by carbon-silicon linkages consist of both (a)vinyl radicals, and (5) methyl radicals, all the aforementionedydrocarbon radicals being present in the ratio of from about-l.2 to 1.8total hydrocarbon radicals per silicon atom and the vinyl radicalscomprise from-'ltoZO per cent of the total number of silicon-bondedhydrocarbon radicals.

5. A resinous composition of matter comprising a polymerizablemonovalent hydrocarbonsubstituted polysiloxane wherein the hydrocarbonradicals attached thereto by carbon-silicon linkages consist of both (a)vinyl radicals, and (b) phenyl radicals, all the aforementionedhydrocarbon radicals being present in the ratio of from about 1.2 to 1.8total hydrocarbon radicals per silicon atom and the Vinyl radicalscomprise from 1 to 20 per cent of the total number of silicon-bondedhydrocarbon radicals.

6. A resinous composition of matter comprising a polymerizablemonovalent hydrocarbonsubstituted polysiloxane wherein the hydrocarbonradicals consist of both (a) vinyl radicals, and (5) both methyl andphenyl radicals, all the aforementioned hydrocarbon radicals beingpresent in the ratio of from 1.2 to 1.8 total hydrocarbon radicals persilicon atom and are directly attached to the polysiloxane silicon atomsby carbon-silicon linkages, the said vinyl radicals comprising from 1 to20 per cent of the total number of silicon-bonded vinyl, methyl, andphenyl radicals.

DALLAS T. HURD.

References Cited in the file of this patent I UNITED STATES PATENTSNumber Name Date 2,155,591 Garvey Apr. 25, 1939 2,273,891 Pollack et al.Feb. 24, 1942 2,426,121 Rust et all Aug. 15, 19%? 2,427,640 Whitehill etal. 1 Sept. 16, 1947 2,445,794 Marsden July 27, 1948 2,465,731 KropaMar. 29, 1949 2,486,162 Hyde et a1. Oct. 25, 1949 2,505,431 Rust et al.Apr. 25, 1950 2,595,728 Swiss et al. May 6, 1952

1. A RESINOUS COMPOSITION OF MATTER COMPRISING A POLYMERIZABLEMONOVALENT HYDROCARSUBSTITUTED POLYSILOXANE WHEREIN THEHYDROCARBONRADICALS CONSIST OF BOTH (A) VINYL RADICALS, AND (B)MONOVALENT RADICALS SELECTED FROM THE CLASS CONSISTING OF ALKYL AND ARYLRADICALS, ALL THE AFOREMENTIONED HYDROCARBON RADICALS BEING PRESENT INTHE RATIO OF FROM 1.2 TO 1.8 TOTAL HYDROCARBON RADICALS PER SILICON ATOMAND ARE DIRECTLY ATTACHED TO THE POLYSILOXANE SILICON ATOM AND AREDIRECTLY CARBON-SILICON LINKAGES, THE SAID VINYL RADICALS COMPRISINGFROM 1 TO 20 PER CENT OF THE TOTAL NUMBER OF SILICON-BONDED HYDROCARBONRADICALS.